tests/test-dispatch.py.out

hgweb: don't raise an exception when displying empty repos

The nullid node claims it's in the default branch, but the branch dict
is empty.  This fixes the main symptom from issue696, but we may want
to set branchtags()['default'] = nullid somewhere for empty repos.

running: init test1
result: None
running: add foo
result: None
running: commit -m commit1 -d 2000-01-01 foo
result: None
running: commit -m commit2 -d 2000-01-02 foo
result: None
running: log -r 0
changeset:   0:0e4634943879
user:        test
date:        Sat Jan 01 00:00:00 2000 +0000
summary:     commit1

result: None
running: log -r tip
changeset:   1:45589e459b2e
tag:         tip
user:        test
date:        Sun Jan 02 00:00:00 2000 +0000
summary:     commit2

result: None